This invention relates to terminal block assemblies of the type used for terminating telephone lines on main distribution frames or like supporting surfaces.
The invention is also concerned with a novel and improved insulation displacement clip type of terminal for use with such a terminal block assembly.
The type of terminal block assembly with which the present invention is concerned has a dielectric body which mounts a plurality of terminal clips that are kept in place relative to the body by a retaining plate. Moreover, the retaining plate may be used to mount the block directly to a board, frame or other supporting surface. In applications where it is desired that the cable bundle be run under the terminal block, an additional standoff bracket may be mounted on the supporting surface, and be provided with means for removably supporting the terminal block.
One particularly advantageous type of terminal block assembly is shown in Troy U.S. Pat. No. 3,957,335 issued May 18, 1976. In the terminal block assembly of Troy, a dielectric body portion is provided with a plurality of side-by-side rows of holes through which the electrically conductive terminals project These terminals have wire receiving portions on one side thereof, and base portions on their opposite sides The retaining plate is arranged to slidably interfit over the body portion such that the terminal base portions are confined between the retaining plate and the surface of the body on which the side-by-side holes are formed, and through which the wire-receiving portions of the terminals project.
Preferably, these terminals comprise clip-type terminals, generally of the type shown, for example, in Sedlacek U.S. Pat. No. 3,636,500, issued Jan. 18, 1972. However, unlike the terminals shown in the Sedlacek patent, these terminals do not have further wire-wrap posts or other projections projecting from their base portions Moreover, these terminals are preferably provided with two or more clip-type terminals projecting from a common base portion. In all other respects, the terminals employ a pair of cantilevered arms which project to form a narrow slot therebetween which is gapped apart somewhat by coining of the material of the arms along some portion of the slot. Preferably the coining is done where the slot meets an enlarged recess formed between the terminal arms, which imparts resiliency to the arms.
Additionally, a lead-in portion is provided in the form of an open-ended generally V-shaped notch which forms the open top portion of the terminal and extends downwardly into the slot portion. The open end of the notch portion is significantly wider than the slot to permit passage of a wire conductor with insulation downwardly into the slot portion. The open end of the notch portion is significantly wider than the slot to permit passage of a wire conductor with insulation thereon freely therethrough. When the wire conductor reaches the junction of the notch and the somewhat spread apart slot portion, the relatively sharp and substantially 90.degree. corner edges of the slot slice the insulation therefrom. The conductor portion of the wire is thereafter tightly held within the slot in electrically conductive contact with the terminal. The provision of such multiple terminals on a common base allows the interconnection of multiple wires for purposes of making connections between incoming cables and inside equipment, for example. While the type of terminal block assembly and terminals described in the above-mentioned U.S. patents have proven highly successful in practice, there is room for further improvement.
The cost of manufacturing terminal blocks and terminals of the type shown in the above-mentioned patents has been steadily increasing. A significant portion of this increase is the raw material costs and particularly the cost of the copper material from which the terminal clips are fabricated. Accordingly, we have attempted to produce a modified clip and block which utilizes substantially less copper material and yet produces a clip and block which have the same external dimensions, so that the block can be used in existing installations.
More particularly, we have redesigned the clip so that the wire receiving portion thereof has a substantially identical appearance and configuration to that of the clip shown in the aforesaid patent to Troy but of reduced thickness. The base portion thereof, which is mounted within the terminal block, is also of reduced thickness and also of substantially reduced dimensions resulting in a substantial overall reduction in weight of the clip as a whole. We have also redesigned the clip so that the performance of the clip will not change in spite of this reduction of weight. That is, the redesigned clip retains an acceptable level of stress, deflection and gripping force between the cantilevered arms thereof to give substantially the same performance in stripping insulation from a wire and thereafter retaining a wire, when a wire is pushed into the clip. Moreover, the same tools presently in use in the field with the present terminal clip and block may be used with our new terminal clip and block. That tool may be of the type shown in FIGS. 6 and 7 of the above-mentioned Sedlacek patent.